Purification of porous materials.



i 1 the electrical arts.

, .fiberfit is customary to treat sheets of I cellulose'by assing them through a strong -ments in the Purification of Porous Matc- N E ewes WILLIS R. WHITNEY, or ALPLAUS, NEW YORK, ASSIGNOR TO GENERAL 1 j A CORPORATION or NEW YORK. 1

. PATE ELECTRIC COMPANY,

I PURIFICATION OF POROUS MATERIALS.

Specification 01 Letters Patent;

Iatented June 1, 1909;

To all whom it may concern: I

' Be it known that I, WILLIs R. WHITNEY, a

citizen of the United States, residing at Alplaus, count of Schenectady, town of Glenvi-lle, and tate of New York, have-invented certain new and useful Improverials, of which the following is a specification.

- solutions from'porous material, by subject- 7mg the material to the influence of an electric otherv impurity to be removed but which is" itself inertand harmless with respect to the My present invention relates to a process of removing impurities such as salts and their current while suspended in a suitable solvent. In addition to this electrical treatmen't I use as the solvent, one which is sub- "stantially isotonic with respect to the'salt or porous material to be purified.

1 My invention is readily applicable to the purification of any porous material containin a salt or com ound wh l l int) .1

tion, but as s owing a specific embodi-f ment of my improved process I have hereinafter described it as applied to the manufa.c. ture' of the insulating compound commonly known in the electrical arts as fit er.

This

I material is somewhat similar to hard rubber in its electrical and mechanical properties, and is used fora great variety of purposes in In ,the manufacture of I solution of c lorid of zinc, after which the A pressed into a homogeneous mass.

I chlorid is then removed by washing.- This -washing is usually performed in several dissheets are piled one. on another'and com- The zinc I .tinct steps by suspending the porous mass in different zinc cblorid solutions of diminishing concentration until pure water is reached, for it has been found that if the material is ure water the osmotic will draw inan excess of water and form waterblisters. These blisters cause splits in the final product and are the cause of the great losses in material which sometimes 7 occur even when extreme care is taken to rep vent their formation by gradual, rather t an by rapid washing. The thicker the sheet to be produced, the greater the difiiculty due to osmotic pressure, and consequently, the

greater the time and care necessary'to remove the zinc chlorid, the complete removal of which is imperative. On this account, six weeks of washing by gradual treatment with more and more dilute solutions of the 'chlorid is necessary for sheets of an inch or more in thickness, thus greatly increasing the cost of material when made in thick masses.

The osmotic pressure of a solution depends on its concentration. The rate of difiusion of-a salt from a concentrated solution to a dilute solution depends on the concentration to that particular salt alone, and not wit respect to other soluble substances which may be carried in one or the other solvents. These factors I make use of in my improved process by utilizing, as a solvent for the zinc chlorid,

the zinc chlorid solution to be removed. By isotonic I mean a solution having sucha con.- centration that it'willhave the same osmotic pressure as the zinc chlorid solution to be removed. Thus, for example, a solution of glycerin or glucose in water may beuscd to wash the fiber mass and thereby remove the zinc chlorid previously employed in the chemical preparation of the mass. In tihs way the concentration of zinc chlorid in the Wash water is ke t low and consequentlyi'ts rate of diffusion rom the mass into the wash water is very high. The osmotic pressure of the washing solution being high, and of any desired predetermined value, does not allow the formation of water} blisters in the fiber. The solution of glycerin or glucose in water used as wash water is not in any way detrimental to the product.

Although, I have described this phase of my process as a plied to the manufacture of fiber it will e understood that it is not limited to such use, but is applicable to a great variety ofwork and involves broadly the use of solutions of harmless material to drive out an approximately isotonic solution from the interstices of porous material.

As heretofore stated, I contemplate the use of anelectric current to increase the vepurity, such as the zinc and chlorin ions com posing the zinc chlorid Within the porous material. Theapparatus for carrying out this current and suitable electrodes laced in the glucose or other washing ii iii and so arranged that the fiber ina s eet, or in any differences of the two solutions with res ect' locity of motion of the ions of the salt or imfeature of my improved process may be very simple consisting principally of a source ofv a solutionwhich is isotonic with respect to current causes the motion of zinc to the cathby th impurity and contains a vously impressing a voltage on said solvent to convenient form can be passed through the metallic salt from a porous material which washing liquid between t e electrodes. The consists in washing sald material with a substantially isotonic solution of an organic substance. v

4. The rocess of removing zinc chlorid from cellulbse which consists in washing said cellulose tion of an organic substance.

5. The rocess of removing zinc chlorid from cellu ose which consists in washing said cellulose with a solution of an organic sube components, of water which from an stance, and simultaneously passing a current electrochemical point of view are H and .OH through said solution to accelerate the reions. moval of said zinc chlorid;

In a divisional application, Serial No. l 6. The process of removing a solution of 475,27 5, filed by me January 30, 1909, claims i an inorganic material from a porous organic are made broadly on the process of removing material, which consists in washing said an ionized impurity from porous material by or anic material with a substantially isotonic the electrolyizng action of an electric current. solution of a substance whichleaves no in- What I claim as new and desire to secure i organic residue in the porous material. by Letters Patent of the United- States, is, 7. The rocess of removing zinc chlorid 1. The process of removing an impurity I from cellu ose, which consists in washing said from a porous material which consists in cellulose with a solution having ap reciable washing said material with a sol ent which osmotic pressure and a relatively ow zinc is substantially isotonic with respect to said chlorid content. I impurity and contains a relatively small I 8. The process of removing a solution of a quantity of said impurity. metallic salt from an organic material, which 2. he process of removing an impurity 1' from a porousmaterial which consists in washingisaid material with a solvent which is substantiallyisotonic with respect to said i relatively small and simultane ode and of chlorin to the anode'and these two elements are thus separated at the electrodes. By a suitable addition -of alkali and acid in dilute form to neutralize the products liberated at the electrodes and to preserve the isotoniccondition of the washing liquid the process practically amounts to the replacement of the zinc and chlorin within the fiber lution relatively high in organic content and relatively low in inorganic content.

In witness whereof, I have hereunto set my hand this 16th day of Janua 1906. l WILLIS. R. W ITNEY.

- VVitnessesL BENJAMIN B. HULL, -HELEN ORFORD.

quantity of said impurity,

accelerate the removal ofsaid impurity.

3. The process of removing a solution of a l consists in washing said material 'with'a so-' with a substantially isotonic solu- 

